Check valve



FIG. 1 is a perspective view of a check valve showing our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines shown in the figures are for the purpose of illustrating portions of the check valve which form no part of the claimed design. 

CLAIM We claim the ornamental design for a check valve, as shown and described. 